Dynasore protects the ocular surface against damaging oxidative stress.

Water soluble "vital" dyes are commonly used clinically to evaluate health of the ocular surface; however, staining mechanisms remain poorly understood. Recent evidence suggests that sublethal damage stimulates vital dye uptake by individual living cells. Since cell damage can also stimulate reparative plasma membrane remodeling, we hypothesized that dye uptake occurs via endocytic vesicles. In support of this idea, we show here that application of oxidative stress to relatively undifferentiated monolayer cultures of human corneal epithelial cells stimulates both dye uptake and endocytosis, and that dye uptake is blocked by co-treatment with three different endocytosis inhibitors. Stress application to stratified and differentiated corneal epithelial cell cultures, which are a better model of the ocular surface, also stimulated dye uptake; however, endocytosis was not stimulated, and two of the endocytosis inhibitors did not block dye uptake. The exception was Dynasore and its more potent analogue Dyngo-4a, both small molecules developed to target dynamin family GTPases, but also having off-target effects on the plasma membrane. Significantly, while Dynasore blocked stress-stimulated dye uptake at the ocular surface of ex vivo mouse eyes when treatment was performed at the same time as eyes were stressed, it had no effect when used after stress was applied and the ocular surface was already damaged. Thus, Dynasore could not be working by inhibiting endocytosis. Employing cytotoxicity and western blotting assays, we went on to demonstrate an alternative mechanism. We show that Dynasore is remarkably protective of cells and their surface glycocalyx, preventing damage due to stress, and thus precluding dye entry. These unexpected and novel findings provide greater insight into the mechanisms of vital dye uptake and point the direction for future study. Significantly, they also suggest that Dynasore and its analogues might be used therapeutically to protect the ocular surface and to treat ocular surface disease.

Nutrient-enriched Infant Formula Is Associated With Higher Weight Gain for Low Birth Weight Infants.

OBJECTIVE: Nutrient-enriched formulas were developed to provide extra nutrients and facilitate optimal growth for low birth weight infants. This study examined the association between use of nutrient-enriched formulas and weight gain among low birth weight infants (birth weight 1500-2500 g). METHODS: This retrospective cohort study used data from infants enrolled in the Illinois Special Supplemental Nutrition Program for Women, Infants, and Children. Analyses were limited to infants born in 2010 with low birth weight (1500-2500 g, n = 3130). We examined weight gain by use of nutrient-enriched versus standard term formula, which was assigned to the infant by the Women, Infants, and Children program during the first month of life. The analyses used a multilevel mixed-effects linear regression model with random intercepts to determine the association between use of enriched versus standard term formula and weight gain while simultaneously adjusting for confounders including gestational age, birth weight, and history of breast-feeding. RESULTS: Among 670 infants in the 1500 to 1999 g birth weight group, those fed enriched formula gained 46.4 g (95% confidence interval 7.4-85.3, P < 0.05) more per month in the first 6 months, and 34.0 g (95% confidence interval -0.4 to 68.3, P = 0.05) more per month >6 to 12 months of age compared with infants using standard term infant formula after adjustment for covariates. Similar findings were noted among the 2460 infants in the 2000 to 2500 g birth weight group. CONCLUSIONS: Use of nutrient-enriched formulas is associated with higher weight gain in low birth weight infants.